Hydrauuc radial engine



April 2o, 1954 T MLLER 2,675,763

HYDRAULIC RADIAL ENGINE Filed Sept. 14, 1948 fr. L

Patented Apr. 20, 1954 HYDRAULIC RADIAL ENGINE Theodor Mller, Winterthur, Switzerland, assignor to Schweizerische Lokomotivund Maschinenfabrik, Winterthur, Switzerland Application September 14, 1948, Serial No. 49,139

Claims priority, application Switzerland September 22, 1947 Claims. (Cl. ID3-161) My present invention relates to improvements in expansible chamber type motors or pumps comprising a moving radiating cylinder block, reciprocating pistons and a rotating outside abutment; and in particular to an improved construction of the enlarged piston heads and of the correspondingly extended cylinder walls of such engines in which the piston end remote from the cylinder working space abuts slidably against a flat face of the abutment, and in which a pressure chamber is recessed from the said piston end, which chamber is supplied with pressure fluid from the appurtenant cylinder space in order to substantially counter-balance the pressure exerted by the operating fluid on the inner piston face.

The principal object of my present invention is to bring the piston head closer to the abutment face and to reduce the lateral pressures against the piston guideway, which result from the friction arising on the abutment face. According to my present invention, therefore, the enlarged piston head is guided in a guideway which is rigidly secured to the cylinder and has a greater diameter than the latten The free end of the said gudeway extends into close proximity of the piston abutment face at the inner dead-center position of the piston. The enlarged piston head is made of such length as to be still enclosed by the said guideway for a short distance also in the outer dead-center position of the piston.

In the drawing, Fig. 1 is a longitudinal sectional view of a piston of known type, and Fig. 2 is a view on the piston head, partly drawn in section, in the direction of the arrow A in Fig. 1.

Fig. 3 shows an engine of the type indicated in section on the line III-III of Fig. 4,

Fig. 4 a side View thereof in section on the line IV-IV of Fig. 3,

Fig. 5 the piston head in larger scale, and

Fig. 6 a. plan view of the piston head of Fig. 5, in direction of the arrow B in Fig. 5.

Fig. 7 is a fragmentary sectional View similar to Fig. 5 showing a modified piston.

In known engines of the type indicated, of which a piston form is shown. in Figs. 1 and 2 of the accompanying drawing, that face of the piston head I5 which serves as abutment face, is larger than the cross-section of the appurtenant working cylinder I9. The enlarged head I5 is of disadvantage in that the cylinder wall guiding the piston cannot be brought closer down to the abutment face Il than is permitted by the height of said head I5, as shown by dash lines at 35 in Fig. 1, so that frictional forces arising on said face II give originto detrimental lateral pressures on the guideways of the piston in the cylinder. A guideway of maximum length also is desirable, however, with respect to eventually present stay ledges 21 (Figs. 1, 2) which s-erve for preventing too great a detachment of the piston head from the said face Iii. Even when two such ledges 2l are provided for, first one thereof will abut-in case of slight irregularities-against the rear side of the head l5 and give rise to an eccentric pull which also may cause very inconvendent lateral pressures on the piston, which pressures may lead to a seizing of the piston.

According to Figs. 3 and 4, the cylinder block 3 comprising three radially disposed cylinders is mounted rotatably on the control stud 2 which. is rigidly secured to the casing l. In the latter, further, the abutment 5 is mounted rotatably at 5 and l and eccentrically to the axis of stud 2, and is so coupled to the cylinder block 3, by means of a follower 9 in form of a cross-loop or universal coupling, that the cylinder block 3 and the abutment 5 always rotate at the same number of revolutions. On the inside wall of abutment E, which may be driven through the stub shaft I9 when the engine shall operate as a pump, three flat faces I I are provided, against which the heads of the pistons I2, I3 abut.

The piston I2 through its slide shoe or piston head I5, abuts directly against the appurtenant supporting face II. The pistons i3, however, ci which only one is fully shown, abut against their faces M through the intermediary of an adjustable spherical segment 28.

Bores 4 are provided in the said fixed control stud 2 and serve for supplying and delivering the operating fluid, e. g. in the sense of the arrows shown in Fig. 4. The cylinders situated above the horizontal median plane of the stud 2, communicate with the upper bore 4, and the cylinders situated below the said plane communicate with the lower bore 4. The web 8 separates the suction and the pressure space of the engine from each other.

A shallow pressure chamber I6 defined by the narrow annular face 23 is recessed from the nat end face of segment 28 of the piston I3 (Fig. 5), which face abuts against the supporting face Il of rotor 5. The said chamber is supplied with pressure uid from the cylinder interior I9 through the bores 20 and 30, thus counter-balancing the pressures exerted by theoperating iluid onto the inner piston face 22. The spherical segment 28 permits slight deviations of the longitudinal axis of the piston from a line standing at 3 right angles to the abutment or supporting face H.

The enlarged piston head 32, in which the spherical face of the segment 28 is mounted, is guided, in accord with my present invention, by means of twordiametrically opposite guideways 33 rigidly secured to the cylinder 3. The said ways 33, at the inner dead-centre position of the piston I3, with their free ends 35 extend very closely to the said face l l, as shown by the dash lines in Fig. 5. Further, the enlarged piston head 32 is of such length that, also at the outer deadcentre position of the piston, the latter will not eave the guideways 33 and will still be engaged thereby over a short distance, as shown in Fig. 5.

In order to prevent the piston from being raised too much from the abutment or supporting face i i, retaining ledges 27 are provided on the abutment and are engaged in a groove 34 of the piston head 32. The guideway 33 is interrupted on the sides where the ledges 2l are engaged by the piston head, so that the guideway engages the piston head only between the ledges 2 by means oi two lugs. In the modification shown in Fig. 7, the piston head is constructed in the same Inanner as in Fig. 5, but instead of with a continuous circular groove 315i, the piston end portion is provided with two opposite peripheral slots 35 in engagement with the two diametrically opposite ledges 2l. The piston is thus prevented from being unduly raised 01T the abutment face l= i and from rotating freely about its longitudinal axis.

A retaining ledge 2i also may be provided on one side only of the piston, in which case the guideway 33 may be cut back on this side only and be 'sept complete on the opposite side.

rEhe invention also may be applied to engines which are operated by means of a gas as operating or pressure iluid respectively.

What I claim as new and desire to secure by Letters Patent is:

1. A fluid operated radial piston engine comprising a casing, a rotor movable in said casing, a cylinder block having radial cylinders eccentrically mounted in said rotor, a piston operating in each radial cylinder, each piston having a body portion slidably engaged within the cylinder and an enlarged end portion, said rotor being provided with flat abutment faces in sliding engagement with the enlarged piston ends, each piston end having a pressure chamber recessed therein, the piston being provi-:led with a longitudinal bore connecting said pressure chamber with the cylinder space to supply pressure fluid from the cylinder space to the pressure chamber, extensions on said cylinders forming guideways for the enlarged piston end portions, said guideways being of such radial length as to arrive in close proximity of said piston end supporting abutment faces at inner dead center position of the piston, and the enlarged piston end portions being of such length to remain engaged by said guideways at outer dead center position of the piston, each piston having the enlarged end portion provided with a peripheral recess, and retaining means carried by the rotor and engaging said peripheral recess in the piston end portion to prevent the piston 4 from being unduly raised on said abutment face.

2. A uid operated radial p-iston engine as claimed in claim 1, wherein said piston retaining means is formed by two diametrically opposite ledges carried by the rotor and penetrating between said guideways to engage a circumferential groove provided in said enlarged piston end portion.

3. A iluid operated radial piston engine as claimed in claim 1, wherein said piston retaining means is formed by two diametrically opposite ledges carried by the rotor and penetrating between said guideways to engage two opposite peripheral slots in said enlarged piston end portion.

4. A uid operated radial piston engine as claimed in claim 1, wherein said enlarged piston end portion is provided with a recess having a spherical bottom, a spherically curved segment being engaged in said recess and having a fiat end face provided with said pressure chamber and slidably engaging said flat abutment face on the rotor.

5. A fluid operated pump or motor comprising a cylinder blocl; having radial cylinders, a piston operating in each cylinder each piston having a body portion slidably engaged within the cylinder and an enlarged end portion, a thrust member surrounding said cylinder block, said thrust me i-- ber being provided with flat abutment faces in sliding engagement with the enlarged piston ends, each piston end having a pressure chamber re cessed therein, the piston being provided with a longitudinal bore connecting said pressure chamber with the cylinder space to supply pressure uid from the cylinder space to the pressure chamber, extensions on said cylinders forming guideways for the enlarged piston end portions, said guideways being of such radial length as to arrive in close proximity of said piston end supporting abutment faces at inner dead center position of the piston, and the enlarged piston end portions being of such length as to remain engaged by said guideways at outer dead center position of the piston, each piston having the enlarged end portion provided with a peripheral recess, and retaining means carried by the thrust member and engaging said peripheral recess in the piston end portion to prevent the piston from being unduly raised off said abutment face.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 388,522 Beauchemin Aug. 28, 1888 580,838 Almond Apr. 20, i897 1,398,788 Mayer Nov. 29, 1921 1,649,347 Hardt Nov. 15, 1927 2,166,114 Benedek AJuly, 18,1939

2,173,432 Benedek Sept. 19, 1939 2,280,859 Neuland Oct. 28, 1941 2,293,692 Wylie Aug. 18, 1942 FOREIGN PATENTS Number Country Date 21,119 Norway 1911 

